1. Field of the Invention
The present invention relates to a collision object determination device of a vehicle for determining collided obstructions, especially, pedestrians or the like.
2. Related Art
Recently, various safety measures of a vehicle including a safety measures of an inside space of the vehicle has been taken into consideration. Specifically, a device for effectively protecting a pedestrian when a collision between the vehicle and the pedestrian occurred has been proposed. In the device for protecting the pedestrian, the device must first be able to accurately determine whether the collision object is a pedestrian or not.
For example, in JP-A-2002-127867, a technology is disclosed in which a plurality of acceleration sensors are provided in an inner surface of a bumper face of a front bumper in the width direction of the vehicle, and the collision object is determined by processing signals from the acceleration sensor in a controller. Specifically, the determination process is performed, using a fact that a ratio of a maximum value of an amount of deformation with respect to a maximum value of a deforming speed is smaller when a collision object that is smaller than a particular collision object, such as a pedestrian. That is, if an acceleration exceeds a predetermined threshold value, a time period is set. Then, a gate, during a term from a time when the deforming speed fall below a threshold value after the deforming speed exceeds the threshold value and reaches a maximum value to a time when the time period is expired, is set. During the term, a signal at a state in which the amount of displacement is within a predetermined width is generated. Then, a signal is generated due to an AND condition of the signal and the gate, and the corrosion with the pedestrian is determined on the basis of the signal.
However, in JP-A-2002-127867, since the acceleration sensors is provided at the bumper, when the collision is occurred during a vehicle speed reduction, deceleration generated in the vehicle by the speed reduction is also detected in addition to the deforming acceleration of the bumper. Due to this, there is a problem that, even though the collision object is same, output values of the acceleration sensor are different between cases that the vehicle is in the speed reduction and in a constant speed. Therefore, a precise determination of the collision object cannot be made. In addition, without being limited by driving at a reduced speed, even if driving is accelerated during a collision, the output value thereof is made to be different from the output value when the vehicle is in the constant speed.